Processors, memory devices, imagers and other types of microelectronic devices are often manufactured on semiconductor workpieces or other types of workpieces. In a typical application, several individual dies (e.g., devices) are fabricated on a single workpiece using sophisticated and expensive equipment and processes. Individual dies generally include an integrated circuit and a plurality of bond pads coupled to the integrated circuit. The bond pads provide external electrical contacts on the die through which supply voltage, signals, and other electrical parameters are transmitted to and from the integrated circuit. The bond pads are usually very small, and they are arranged in an array having a fine pitch between bond pads. The dies can also be quite delicate. As a result, after fabrication, the dies are packaged to protect the dies and to connect the bond pads to another array of larger terminals that is easier to connect to a printed circuit board.
Conventional processes for packaging dies include electrically coupling the bond pads on the dies to an array of pins, ball pads, or other types of electrical terminals, and then encapsulating the dies to protect them from environmental factors (e.g., moisture, particulates, static electricity, and physical impact). In one application, the bond pads are electrically connected to contacts on an interposer substrate that has an array of ball pads. For example, FIG. 1A schematically illustrates a conventional packaged microelectronic device 6, including a microelectronic die 10, an interposer substrate 60 attached to the die 10, a plurality of wire bonds 90 electrically coupling the die 10 to the interposer substrate 60, and a casing 70 protecting the die 10 from environmental factors.
FIG. 1B schematically illustrates another conventional packaged microelectronic device 6a having two stacked microelectronic dies 10a-b. The microelectronic device 6a includes a substrate 60a, a first microelectronic die 10a attached to the substrate 60a, a spacer 30 attached to the first die 10a with a first adhesive 22a, and a second microelectronic die 10b attached to the spacer 30 with a second adhesive 22b. The spacer 30 is a precut section of a semiconductor wafer. Other types of conventional stacked microelectronic device packages include an epoxy spacer, rather than a section of a semiconductor wafer, to space apart the first and second dies 10a-b. The epoxy spacer is formed by dispensing a discrete volume of epoxy onto the first die 10a and then pressing the second die 10b downward onto the epoxy. Epoxy spacers, however, are not rigid until cured, and thus the second dies may not be uniformly spaced apart from the corresponding first dies.